As Guru said, I use typically GPL for source code that I write myself. For code that I’ve derived from someone else’s work, I honour whatever license they specified, which is mostly GPL but you sometimes see BSD or other licenses too.
For hardware designs the situation is a bit more complicated because it doesn’t quite fall under the same legal framework as text or artwork. The basis of the GPL is copyright, so it uses the rights given to the creator as the copyright holder to allow them to use those rights to dictate how the work should be shared. It blew my mind when I first figured out that Open licenses actually require copyright (which is designed to limit what can be done with a work) for the license to work properly and enforce that the work can be shared. It’s a clever legal hack.
But things like CAD files (board designs) aren’t classified as “art” or “creative works” legally, so applying the GPL to a hardware design is very shaky. It probably wouldn’t be enforceable in court. To solve that problem there are licenses such as the TAPR Open Hardware License (which I normally use) that were specifically written to have the same intended outcome as the GPL, but to base their mechanism in different legal terms that apply more to hardware. So you can think of the TAPR OHL as being like the GPL, but for hardware.
These days you mostly see the CERN Open Hardware License being used, which is mostly just the TAPR OHL with the name replaced. When CERN started doing a lot of Open Hardware work they needed a license so they used the TAPR OHL, and put their own name on it. Now many people seem to think they invented it, when all they really did was popularise it!
My laser cutter is a Redsail 40W laser engraver that I bought very cheaply from a friend who had a sign writing business. They imported a few of them and then didn’t use them, so I bought one second-hand but unused. Mine is many years old and the controller was absolutely rubbish, so I paid a friend who knew a lot about laser cutters to strip out all the wiring and start from scratch with a new controller.
Newer cutters are probably much better than mine, with more modern controllers, so I wouldn’t use mine as an example of what’s worth getting.